ulnar claw hand versus median nerve benedict hand

[docmo83]

Is a claw hand seen in both median and ulnar nerve injuries? FA confused me on this, and i really would like it clarified!

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[swtiepie711]

Is a claw hand seen in both median and ulnar nerve injuries? FA confused me on this, and i really would like it clarified!

Both median nerve & ulnar nerve injuries can create the same hand (hand of benediction). To distinguish, you'll need other information (sensory defects, other motor defects).

Ulnar nerve lesion: damages the lumbricals of the medial 2 fingers. W/o these, you can't extend the PIP joint. These 2 are fixed in a flexed position (PIPs & DIPs). B/c radial is ok, you're MCP joints are extended. Your median nerve innervates flexor digitorum superficialis & the lateral side of flexor digitorum profundus so you can still flex the 2nd & 3rd digits. Forarm flexors unopposed, flexion of PIPs/DIPS. Basically, the patient can make a fist, but can't extend all fingers. Note sensory loss in the ulnar distribution; thenar eminence sensation & thumb function is a-ok. Middle image p 354 FA 2009.

Median nerve lesion: now you've damaged the flexor dig superficialis & lateral flxr dig profundus. You can't flex your 2nd & 3rd dig. You're medial part of flxr dig profundus is cool cuz it's innervated by the ulnar nerve so you can flex your 4th & 5th fingers. In this case, the patient can extend all their fingers, but can't make a fist. Sensory loss would be in the median nerve distribution & the thumb deficits (opposition) would be noticeable. Note this lesion has to be higher & damage innervation to the forearm muscles. It's also not perfect - the fingers 2 & 3 wouldn't be completely extended. But you've knocked out the flexors (flex DIP/PIP) & the lumbricals (flex MCP) but have unopposed radial nerve action, hence they extended at the . Middle image p 354 FA 2009.

Distal median nerve lesion (say, at the carpal tunnel) would not affect your arm flexors. You would just get screwed up lateral lumbricals. The pt wouldn't be able to extend their PIP joints. Flexors are fine so they will pull these fingers in. Medial fingers 4 & 5 have intact function. You'll end up with the 1st image on p354 FA 2009.

The right image in FA 2009 is the total claw - you've bumped ulnar & median nerves, lost all lumbricles and therefore can't extend PIP/DIP joints. Unopposed radial nerve action has the MCP joints extended.

 

[FutureChiDoc]

Technically, the Pope's Blessing/Hand of Benediction is ONLY the median nerve lesion. They aren't really the SAME lesion.


In the Pope's Blessing, the problem is 2/3 flexion. But 4/5 flex all the way to the palm.

In the Ulnar Claw, 4/5 claw but don't get to the palm. So "Ulnar Claw" and "Pope's Blessing" aren't really the same.

 

[medstudentduh]

Actually swtiepie711 is absolutely correct while FutureChiDoc has a brought up a technically true point, nontheless....

The main difference in the two "Pope's Blessing" hands (as they CAN actually BOTH be referred to as "Pope's Blessing") {median vs. ulnar} is:

With a DISTAL ULNAR Nerve lesion, the patient PRESENTS with "Pope's Blessing" hand.

With a PROXIMAL MEDIAN Nerve lesion, the patient must be asked to make a FIST before "Pope's Blessing" hand can be seen.

Hope this helps!